Spring means



Dec. 18, 1945.

A. B. BERTHELMANN 2,391,120

SPRING MEANS Filed May 29, 1941 2 Sheets- Sheet l ni -damn} J1 I WINVENTOR.

ARTHUR B. BERTHELMANN Dec. 18, 1945. Q B. BERTHELMANN SPRING MEANS FiledMay 29; 1941 2 Sheets-Sheet 2 Jay- INVENTOR. ARTHUR B. BERTHELMANN BY I" practical to replace Patented Dec. 18, 1945 a UNITED STATES PATENTOFFICE e r V SPRING MEANS p 7 Arthur B. Berthelmann, Madison, Wis. IApplication m y 29, 1941, Serial No. 395,808

' '7 Claims.

invention relates to improvements in spring means. V

Coil and/or leaf springs are Well known for use as a means ofresiliently supporting objects, as for example automobile or truckframes, to protect them against sudden jar as would ordinarily occur bydirect connection of the object tov the support. v

These springs operate successfully within the elastic limit of thematerial from which they are made according to vHooks law. Once thespring has been stressed beyond the elastic limit of the material fromwhich it is made, it fails to return to its original unsprung conditionand thereby loses a certain amount of its resistivityv toforce. v

The spring metal from which the-springs are made is subject to failureby fatigue due to repeated flexing thereof over relatively long periodsof time. Y

lation as for example the installation or the so called knee action inautomobiles and the like,

coil springs used therein become fatigued and must be replaced tomaintain the proper alignment of parts, and also to maintain properriding conditions. Since it is a comparatively expensive operation toreplace the springs involved in a knee action assembly, I havediscovered a rectifying or compensator air controlled spring means whichmay be associated in cooperative relationship with the coil spring torevitalize or restore the .spen resistivity of the spring to itsoriginal condition at a minimum of cost, time and labor. V I

Under certain conditions of loading, as for example, an overloadedtruckpr other vehicle, the

leaf springs are. sprungbeyond their normal capacity and therefore donot properly suspend the extra load. The weight must. either be reducedto permit proper functioning of the springs or more resistivesprings-installed. Since it is not economical to' reduce the load, andnot the springs with more resistive ones, since the more resistive onesdo not permit proper, riding'conditions underno load operation of thevehicle, I have discovered that the use. of air-controlled spring meansvasa helper spring in combination with. the leaf springs successfullysolves all conditions of load- 11 Therefore, one objectof my inventionis to provide a spring means, the resistivity of which may be directlycontrolled-by the use of a compressible medium, for example air. I

Under certain conditions of coil spring instala Another object is toprovide an air-controlled spring means adapted to be operativelyassociated with a coil or leaf spring, whereby the original resistivityof the springs is restored, or the resistivity of the springs isincreased by means of the air-controlled spring means.

A further object is to provide a spring means having an air chamberadapted to provide resistance to external force in proportion to theamount of air confined in the air chamber.

A still further object is to provide an air-controlled spring meanshaving a constricted medial portion. which acts to permit biasedmovement of the ends thereof under pressure exerted thereon.

Yet another object. isto provide an air-controlled expansion springmeans including a casing having nested sections and being adapted tolimit the expansion of the spring means.

Still another object is to provide a sprin means assembly including anair controlled spring cushion having means associated therewith wherebythe cushion is automatically returned to unsprung position under normallo'ad ing conditions.

In the drawings:

Fig. 1 is a sectional view showing my improved air-controlled springmeans in combination with a coil spring.

Fig. 2 is a view taken on the line 2-2 of Fig. 3.

Fig. 3 is a sectional view showing a' modified form of my invention.

Fig. 4 is a plan View partly in section showing the spring meansstiffened with air and in combination with a casing.

Like parts are indicated by the same reference numerals throughout theseveral views.

The air-controlled spring means indicated generall by the numeral Itcomprises a tubular wall section H closed at each end with a rigidinsert l2 and l3. 7 I

The wall section is made of any suitable resilient material, as forexample, rubber, and preferably of a comparatively tough rubber similarto the rubber used in the making of automobile tires.

The wall section II is cylindrical in form at the ends [4. Each endtapers conically toward each other to a constricted mid-section orexpandible portion [5. It is at this mid-section that the resistivity ofthe spring means is controlled.

Th wall portion throughout its length II is corded (not shown) with aresilient type of cording which is embedded in the wall and acts tomaintain the unsprung and uninflated condition of the spring means orrubber cushion Ill.

The wall portion II may be molded in the shape shown in Fig. 1, each endof which is formed with a shoulder support IS, on which the inserts I2and I3 are carried.

The inserts l2 and I3 may be made of metal or hard rubber or any othersuitable material shaped in the form of a disc. Each disc is convexrelative to each other for purposes of strength. The inserts are securedin air tight relationship with the shouldered ends of the wall II in anyconvenient manner as by vulcanizing in the case of hard rubber inserts,or

by the use of any suitable bonding agent.

The lower insert I3 is provided centrally a wall must be formed in themanner indicated in thereof with a valve stem ll, of any common type,whereby air or other suitable gas may be inserted into the air chamberIDA to strengthen the wall |I against collapse as hereinafter explained.

In operation the rubber cushion I3 is used in the following manner. If,for example, a coil spring I3, is used to resiliently support a load, asfor example, a vehicle frame, represented in part at IS on any suitablesupport as for example an axle, represented in part at 2|, has beenweakened due to fatigue of the metal from which the spring is made, orothe reasons, and it is desired to compensate for this loss inresistivity, the rubber cushion Ill may be inserted within theconvolutions of the spring I8 having its upper and lower ends in closefitting relationship with the spring at 22 and 23 respectively andhaving ends held in relative alignment and protected by centering cups24 and 25. The centering cup 24 is provided. with a hard rubbercentering means received in the concaved side of the insert I2 to aid insecuring the cushion in alignment.

If the spring I8 has'not been greatly fatigued, the normal resistivityof the rubber cushion II! will be suflicient to offset the loss inresistivity to the spring I8. However, if the spring has becomeconsiderably weakenedythen the resistivity of the rubber cushion may beincreased by the addition of air into the air chamber IDA through thevalve stem I1.

By adding air through the valve stem I! the wall portion II is forcedlaterally outwardly, particularly in the midsection I5 as is clearlyshown in Fig. 4. The addition of air causes the wall to become stiifenedin a manner similar to that of an inflated automobile tire.

By stiffening the wall I I in this manner the resistivity of the cushionis increased and the load to be supported is thereby properly suspended.

When the rubber cushion is compressed by means of external forcesapplied at the opposite ends thereof, the mid-section I5 bulgesoutwardly (not shown) due to the more resilient nature of the wall atthe mid-section, and due to the compression of the air on the inside ofthe cushion forcing the wall at the mid-section out wardly.

It is to be noted that the thickness of the wall II varies from acomparatively thick walled section at each end I 4 to a comparativelythin walled section at the mid-section I5. It is because of thisconstruction that the mid-section of the cushion bulges outwardly undercompressive forces thereby permitting the cushion to act in a mannersimilar to a spring. It is found that a common cylindrical shapedresilient wall will not function in the manner of a spring, but that thethe drawings.

It is noted that the convolutions of the spring I8 acts as a limitwithin which the wall may be expanded. It is found that under extremecondition of loading, it is necessary to increase the air pressurewithin the cushion to such an extent, in order to sufficiently stiffenthe cushion against compression, that there is a tendency for the wallto bulge outwardly beyond its normal limit. In addition to preventingthis by means of the convolutions of the spring I8, a casing 26 has beenprovided which is adapted to enclose the inflated cushion I0.

The casing 26 comprises an upper section 2'! closed at the upper end andtelescopically receivedin a' lowersection 28. The lower end 29 of thesection 28 is provided with an opening 35 through which air means may beconnected to the valve stem II.

Figs. 2 and 3 show a modified form of the in? vention. The spring meanscomprises a pair of cups 3|. Each cup includes a base portion 3'2flaring outwardly into a guidewall 33. Centrally, of each'base portion32, is provided a centering nib 34 adapted to receive the cupped end 35of the spring means 36. l The spring means 36 is formed in a unitarypiece of any suitable material, as for example, rubber of the type' usedin automobile tire construction. The spring means 36 is oval in shape,the opposite ends of which are cupped inwardly at 35 to provide meansfor mounting and centering' the spring means-in operativepositionbetween the cups 3|.

The mid-section 31 of the spring means 36 is. reinforced by means of aresilient rubber flange or fin 38 molded peripherally on the mid-sectionof the spring cushion 36 for purposes hereinafter to be described.

The upper cup 3| is provided with a valve stem opening 39 through whichthe valve stem 40 may extend from the spring cushion 36 all as clearlyshown in Fig. 3. i

The cushion 36 is assembled between the cups 3| by positioning the nibs34 of each cup in a corresponding cupped end 35 of the cushion 35. Thecups 3| are held in relative alignment with each other by means of theguide bolts 4! loosely received in the guide wall 33 to permit relativesliding movement thereon of the cups. The spring cushion 3B is sealedbetween the cups 3| by means of a resilient rubber cover 42 positionedabout the outer end of each guide wall 33. The rubber cover 42 protectsthe cushion 36 against dirt and moisture which would otherwise causedamage to the cushion. A breather hole 43 is provided in the lower cup3| to permit air to breathe in and out between the cups 3| as the cupsare moved toward and away from each other under the action of loading.

The assembled spring meansmay be inserted between a support,fragmentarily indicated at 44, and a body to be supported, fragmentarilyindicated at 45, and held in position by the cups 46. As the body 45 isloaded the cushion 3 6 expands outwardly against the resistive force ofthe rubber flange or fin 38, It is to be noted that the reinforcingflange 38 tends to return the spring cushion'36 to its normal unsprungcondition. Under extreme conditions of loading the spring means 36expands outwardly and the cups 3| approach each other until the guidewalls 33 are immediately adjacent each other. It is to be noted that thwalls are never permitted to come into direct contact with each otherbecause the flange 38 i moved outwardly and disposed between the outeredge of the guide walls 33.

The flange 38 is provided with slots 4! adapted to receive the bolts 4|when the cushion 3B is in the extreme expanded position. Th flange 33therefore serves two useful purposes, one as a resilient means to returnthe cushion to its ori inal unsprung position and the other to act as acushion between the guide walls 33 of the cups 3 l.

The spring assembly may be stiffened against flexure by adding air tothe air chamber 48 through the valve stem 40. The air causes theresilient cupped ends 35 of the spring cushion to be stiffened againstthe nibs 34 of each cup 3 l.

The spring means shown in Figs. 2 and3 may also be used as a helperspring in the case of leaf springs liable to be sprung beyond theirnormal capacity. Under these conditions the spring means 36 is mountedbetween .the leaf springs, as for example those of a truck (not shown),immediately above the axle (not shown) and between the frame of thetruck body. In this manner both the leaf spring and the spring means 36cooperate to suspend the load proportionally. It may be noted that theguide walls 33 of the cup cooperate with the spring cushion 36 to forcethe walls of the cushion outwardly at the flange 38 where the resiliencyof the cushion is concentrated. The guide walls 33 thus preventstraining of the cushion at its weaker sections.

It is to be understood that the spring means hereinbefore described maybe used either alone or in combination with coil and/or leaf springswherever it is necessary to resiliently support a load.

It may be readily realized that the air-controlled spring means mayserve many useful purposes. The spring means may be used to restore theresistivity to a spent spring, or increase its resistivity. The springmeans may be inflated to increase its resistivity under extreme loadingconditions, and then deflated after the loading condition has beenrelieved,thereby providing proper riding conditions under all conditionsof load. It may be economically used in combination with a spent springthereby obviating replacement of expensive parts.

From the foregoing it is apparent that the objects of this inventionhave been accomplished by providing a spring means, having means wherebythe resistivity of the spring means may be varied to provide properresistive supports under any given load condition.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. A pneumatic device of the character described comprising asubstantially cylindrical wall element, said wall element being closedat its upper and lower end to provide a chamber, a valve means incommunicating relationship with said chamber whereby a predeterminedamount of a compressible medium may be inserted into said chamber, and aflexible portion medially said wall element, said portion being of adiameter substantially less than the diameter of the remainder portionof said wall element, said medial portion being adapted to function incombination with said compressible medium to resiliently support saidends of said wall element against movement toward each other.

element being flexible and of a diameter substan-' tially less than thediameter of the remainder 'portion of said wall element, saidmedialportion being adapted to function in combination with said compressiblemedium to resiliently bias said mounting means outwardly relative toeach other.

3. A spring means comprising a tubular element having a sprung .andunsprung position, relatively stiff cup-like members associated withsaid tubular element to form an air chamber therewith, valve meanscarried by said spring means whereby air may be inserted into saidchamber to stiffen said tubular element against change in position saidtubular element having a flexible portion mediallythereof and of adiameter substantially less than the diameter of the remainder of saidtubular element.

4. A spring means comprising a comparatively resilient element, theterminal ends of said element flaring outwardly into a cup-like section,the wall portion of each of said sections being of a greater thicknessthan the thickness of the wall portion of said resilient element, arigid disc member closing said sections to form an air chamber, valvemeans whereby air may be inserted into said chamber to stiffen saidtubular element against flexure.

5. A spring means comprising a comparatively thin walled section, saidsection being relatively resilient v and flaring outwardly at both endsinto a cup-like section, the walls of said cup-like section increasingin thickness and terminating in a shouldered support, a rigid closureelement sealed to each of said shouldered supports thereby providing anair chamber for said spring means, a valve means whereby air may beinserted into said chamber to stiifen said thin walled section againstflexure.

6. A spring means comprising a comparatively thin walled section, saidsection being relatively resilient and flaring outwardly at both endsinto a cup-like section, the walls of each cup-like section increasingin thickness and decreasing in resiliency, shoulder portions adjacentthe end of each cup-like section, an inwardly curved rigid closureelement sealed to each of said shoulder supports thereby providing anair chamber for said spring means, a valve means whereby air may beinserted into said chamber to stiffen said sections against flexure.

7. In combination, a casing including telescopically related sections, aspring means car! ried within said casing, said means including an airchamber the walls of which are gradually tapered mediallyward fromopposite ends thereof to form a single constricted and. substantiallyresilient section, and valve means associated with said spring means,said casing acting to limit the expansion of said air chamber duringinflation of said spring means.

ARTHUR B. BERYITHELMANN.

